Description
Dictyota dichotoma was once regarded as a cosmopolitan species, found through most subtropical and warm-temperate oceans, including Europe from Spain to the Shetlands (South and Tittley 1986), and the western Atlantic from Brazil to VA (Schneider and Searles 1991), and the coasts of Africa, Asia, and Australia (Schnetter et al. 1987). Hoyt (1907) noted variations in breeding biology between European and NC Dictyota 'dichotoma', and distinguished Western Atlantic populations as var. menstrualis. On this basis, as well as morphology and chromosome counts, Schnetter et al. (1987) raised D. menstrualis to full species status. Geographical variation in chemical compounds produced by D. dichotoma populations elsewhere in the world (Europe, Japan, Australia) suggest that this 'species' is actually a species complex (Texeira et al. 1990).
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Protista | Phaeophyta | Phaeophyceae | Dictyotales | Dictyotaceae | Dictyota |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 1961 | Established | Stable | Cryptogenic | Regular Resident | Western Atlantic | Western Atlantic | Shipping(Fouling Community),Fisheries(Oysters-accidental) |
History of Spread
Dictyota menstrualis (Forked Sea Tumbleweed) is found in the Western Atlantic from Wachapreague VA through southern FL and the Caribbean south to Brazil (Humm 1963; Schnetter et al. 1987; Schneider and Searles 1991). Populations from eastern Atlantic Islands (Azores, Madeira, Canaries), collectively referred to as 'Macaronesia', also show morphological features of D. menstrualis (Schnetter et al. 1987).
The northern limit of D. menstrualis' distribution was believed to be Beaufort NC, or Cape Hatteras, just to the north (Hoyt 1907; Hoyt 1927) but in 1962, 'quantities of Dictyota dichotoma (=menstrualis) were found attached to shells and driftng along the marshes east of Wachapreague on the Eastern Shore of VA. The species appears well-established in the area and may have been a constituent of the summer flora there for a long time. This is about 200 miles (~300 km) farther north than its previously known limit, but collections of algae along this section of coastline have been so few in the past that it could easily have been missed. If its occurrence along the Eastern Shore of VA is an annual event, then it is a species that crosses the Beaufort transitional zone' (Humm 1963). The continued presence of D. menstrualis on the VA coast indicates that it has a mechanism of overwintering after its fall dieback (Humm 1979). At Beaufort NC, this seaweed overwinters as germlings, 7-9 cell settled embryos, which have very slow growth at 12 C, but resumed rapid growth when transferred to 24 C (Richardson 1979). We have not found records of D. menstrualis between Cape Hatteras and Parramore Island VA (Schneider and Searles 1991; Zaneveld and Willis 1976).
Humm (1979) attributed the occurrence of Dictyota menstrualis on VA's Atlantic shore to current reversals, permitting transport around Cape Hatteras. However, since Burton's Bay, and other inshore waters near Wachapreague contained man-made oyster reefs (Rhodes 1970), transport with transplanted oysters, as well as transport with fishing or recreational boats are also possibilities. We consider Dictyota menstrualis populations in the Chesapeake region to be cryptogenic.
History References - Hoyt 1907; Hoyt 1927; Humm 1963; Humm 1979; Rhodes 1970; Richardson 1979; Schnetter et al. 1987; Schneider and Searles 1991; Zaneveld and Willis 1976
Invasion Comments
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | 30.0 | |||
| Salinity (‰) | 20.0 | |||
| Oxygen | ||||
| pH | ||||
| Salinity Range | poly-eu |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | 22.0 | 22.0 |
| Typical Adult Size (mm) | 134.0 | 134.0 |
| Maximum Adult Size (mm) | 290.0 | 290.0 |
| Maximum Longevity (yrs) | 1.0 | 1.0 |
| Typical Longevity (yrs |
Reproduction
| Start | Peak | End | |
|---|---|---|---|
| Reproductive Season | |||
| Typical Number of Young Per Reproductive Event |
|||
| Sexuality Mode(s) | |||
| Mode(s) of Asexual Reproduction |
|||
| Fertilization Type(s) | |||
| More than One Reproduction Event per Year |
|||
| Reproductive Startegy | |||
| Egg/Seed Form |
Impacts
Economic Impacts in Chesapeake Bay
Dictyota menstrualis (Forked Sea Tumbleweed) appears to have had no economic impacts in the Chesapeake Bay region.
Economic Impacts Outside of Chesapeake Bay
Dictyota menstrualis (Forked Sea Tumbleweed) is of ecological interest because of its chemical defenses. In its native range, it may influence invertebrate and seaweed species composition and foodwebs, but its overall economic importance on fisheries is unknown.
Ecological Impacts on Chesapeake Native Species
Impacts of Dictyota menstualis (Forked Sea Tumbleweed) are probably limited by the rarity of this species in the Chesapeake region.
Food/Prey, Toxicity - D. menstrualis has been heavily studied, because of its chemical defenses. High concentrations of diterpene alcohols deter most predators, including fishes, amphipods, and sea urchins. However, a few tolerant species, including the amphipod Amphitoe longimana and the polychaete Platynereis dumerilii feed on D. menstrualis and appear to accumulate the deterrent compounds as an anti-predator defense (Duffy and Hay 1990). These herbivores are not restricted chemically or nutritionally to D. menstrualis, but show better survival during periods of high fish predation in comparison to populations on more palatable seaweeds (Duffy and Hay 1994).
References- Duffy and Hay 1990; Duffy and Hay 1994
Ecological Impacts on Other Chesapeake Non-Native Species
Impacts of Dictyota menstrualis (Forked Sea Tumbleweed) on other cryptogenic or introduced species in the Chesapeake region are unknown.
References
Bold, Harold C.; Wynne, Michael J. (1978) Introduction to the Algae: Structure and Reproduction, , Englewood Cliffs, NJ. Pp.Duffy, J. Emmett; Hay, Mark E. (1990) Seaweed adaptations to herbivory, BioScience 40: 368-375
Duffy, J. Emmett; Hay, Mark E. (1994) Herbivore resistance to seaweed chemical defense: the roles of mobility and predation risk, Ecology 75: 1304-1319
Hoyt, W. D. (1907) Periodicity in the production of the sexual cells of Dictyota dichotoma, Botanical Gazette 43: 383-392
Hoyt, W. D. (1910) Alternation of generations and sexuality in Dictyota dichotoma, Botanical Gazette 49: 55-57
Hoyt, W. D. (1927) The periodic fruiting of Dictyota and its relation to the environment, American Journal of Botany 14: 592-619
Humm, Harold J. (1979) The Marine Algae of Virginia, , Charlottesville. Pp.
Humm. H. J. (1963) Dictyota dichotoma in Virginia, Virginia Journal of Science 14: 109-111
Kaplan, Eugene H. (1988) A Field Gude to Southeastern and Caribbean Seashores, In: (Eds.) . , Boston. Pp.
Ott, Franklyn D. (1973) The marine algae of Virginia and Maryland including the Chesapeake Bay area, Rhodora 75: 258-296
Rhodes, Russell G. (1970) Seasonal occurrence of marine algae on an oyster reef in Burton's Bay, Virginia, Chesapeake Science 11: 61-71
Richardson, Jospeh P. (1979) Overwintering of Dictyota dichotoma (Phaeophyceae) near its northern distribution limit on the east coast of North America., Journal of Phycology 15: 22-26
Schneider, Craig W.; Searles, Richard B. (1991) Seaweeds of the Southeastern United States, , Durham. Pp.
Schnetter, Reinhard; Hronig, Ingrid; Weber-Peuckert, Gisela (1987) Taxonomy of some North Atlantic Dictyota species (Phaeophyta), Hydrobiologia : 193-197
South, G. Robin; Tittley, Ian (1986) A checklist and distributional index of the benthic marine algae of the North Atlantic Ocean., , St. Andrews, New Brunswick, and London. Pp.
Texeira, Valeria L., Almeida, Sergio A. D. S., Kelecom, Alphonse (1990) Chemosystematics and biogeographic studies of the diterpenes from the marine brown alga Dictyota dichotoma, Biochemical Systematics and Ecology 18: 87-92
Zaneveld, Jacques S.; Willis, William M. (1976) Marine algae of the American coast between Cape May, N. J. and Cape Hatteras, N. C. III. The Phaeophycophyta, Botanica Marina 19: 33-46